The present invention relates to the field of surface patterning.
Electron beam (“e-beam”) lithography has successfully been employed in a variety of industrial applications to fabricate very small structures. Though often effective, e-beam lithography is slow and expensive for many applications. Techniques therefore have been developed to lower costs and decrease production times. Specifically, e-beam lithography has been used to create a master, from which a stamp may be created. A stamping material (ink) is then applied to the stamp, which is subsequently brought into contact with a surface. The stamping material is transferred to the surface at locations where the stamp contacts the surface. The surface may then be etched to remove surface material at all points that are not coated with stamping material, thereby replicating the stamp.
Stamping of alkane thiols onto a gold surface has been extensively investigated. The alkane thiol is either absorbed into or adsorbed onto the stamp, which is then brought into contact with a gold surface. When chemisorbed to a surface, alkane thiols commonly produce a layer of close-packed, independent chains, which is often used to modify the surface, for example, to alter corrosion resistance and/or electrical properties, or to pattern the surface. Common alkane thiols include octadecanethiol and hexadecanethiol. Alkane thiols are typically applied from solution, e.g., in ethanol or hexane, to surfaces such as gold, silver, or copper.
Although stamping of alkane thiols on gold surfaces has been extensively investigated, to date the method has only proven itself in the laboratory and has not been effectively transferred to industrial settings, because of the complexities of the stamping process. The simultaneous and often contradictory requirements of rapid diffusion and high solubility of the alkane thiol onto the stamp, appropriate mechanical characteristics of the stamp, fast reaction rates relative to surface diffusion rates of the alkane thiol onto the gold substrate, high irreversibility on the gold surface, and resistance of the stamping material to subsequent processing steps have been difficult to achieve. Thus, a central factor limiting adaptation of the laboratory technique to industrial applications is the difficulties encountered while trying to achieve simultaneous control of multiple time-dependent, or rate-dependent, processes.
In view of the drawbacks associated with prior art techniques, it would be desirable to provide methods and apparatus for patterning surfaces that overcome these drawbacks. It also would be desirable to provide methods and apparatus for patterning surfaces that require control of fewer rate-dependent processes. Desirably, these methods and apparatus can be used in industrial applications.